1. Technical Field
The present disclosure generally relates to the field of electrical converters and, more particularly, electrical converters that permit the use of a line voltage switching device as an input to a high-impedance controller input.
2. Description of the Related Art
Electrical devices are frequently automated using one or more line voltage switching devices. At times, the line switching device can be coupled to one or more environmental sensors to permit the electrical load controlled by the switching device to respond to the occurrence of one or more events. An example includes electrical devices such as access control arm motors that automatically rise when the motion associated with an approaching vehicle is detected. Another example includes electrical devices such as luminaires that automatically illuminate when a change in ambient light level is detected. Other sensors such as proximity sensors, stress and strain sensors, load cells, and the like may also be electrically and operably coupled to a switching device rated for use at relatively high line voltages (e.g., 90 VAC to 600 VAC) and at relatively high currents (e.g., milliamps and higher).
The design and materials of construction selected for the electrical contactors and the switching device are based upon the expected conditions found in line voltage service. For example, electrical contactors may be designed to handle the arcing and high current flows that sometimes accompany opening or closing the switching device controlling the line voltage supply to an electrical device. In many instances, the design and materials of construction of the electrical contacts in the switching device may include silver or other metal alloys upon which oxides and sulfides form during normal operation. At line voltage and current, such oxides and sulfides may present a negligible resistance to the passage of current through the contacts. However, at lower voltages (e.g., 3V to 24V) and currents (e.g., microamps) such as those used for logic level signaling, the impedance presented by contaminants including oxide and sulfide accumulations can hinder or even prevent the transmission of current through the contacts. Thus, line voltage switching devices, particularly those remaining in satisfactory condition and having significant remaining service life after use in line voltage switching applications, are typically unsuitable for use in applications where the switching of relatively low voltage and relatively low current signals is required.
In response to the increasing emphasis placed on energy efficiency, many replacement electrical devices are fully or partially automated or operated using one or more low voltage or solid state control devices or controllers. Such solid state controllers provide significant flexibility in the operation of the electrical device, often while providing energy saving benefits. In many instances, the retrofitting of traditional electrical devices with energy efficiency replacements (e.g., replacing high-intensity discharge or metal halide light sources with solid state light sources) is performed in conjunction with the installation of one or more solid state controllers or processors to control the replacement electrical device.